Rotary hydrostatic machine



March 13, 1962 H. ERDMANN 3,

ROTARY HYDROSTATIC MACHINE Filed Oct. 6, 1959 3 Sheets-Sheet 1 I N V ENTOR 94/145 [/PD/VA/V/V March 13, 1962 H. ERDMANN 3,

ROTARY HYDROSTATIC MACHINE Filed Oct. 6, 1959 3 Sheets-Sheet 2 Mxw March13, 1962 H. ERDMANN 3,024,736

ROTARY HYDROSTATIC MACHINE Filed Oct. 6, 1959 3 Sheets-Sheet 3 FIG. 3

WSW

United States Patent Office 3,024,735 Fatented Mar. 13, 1962 3,024,736ROTARY HYDROSTATIC MACHINE Hans Erdmann. Frankfurt am Main. Germany, asienor to Alfred Teves Maschinenund Armaturenfabrik K.G., Frankfurt amMain. Germany Filed Oct. 6, H59, Ser. No. 844,309 Claims priority.application Germany May 14, 1959 Claims. (Cl. 103136) The inventionrelates to a rotary hydrostatic machine, serviceable as a pump or as amotor, having vanes displaceable in radial recesses of a rotor. andvalve disks installed in the housing on both faces of the rotor. Thedisks are the lateral walls of compartments formed with the vanes. therotor and a cam ring.

When such machines are to achieve a large delivery at low rotationalspeed. as for example in hydraulic motors required to start under load,the problem is to minimize leakage of medium across the edges of thevanes along the cam contour and laterally at the vane edges. from onecompartment to the next, while at the same time avoiding friction andwear, and maximizing efliciency. in known displacement motors. thisobject is pursued by preventing deflection of the side walls by rigidityof construction or by subjecting one wall on its reverse side to acompensating pressure, corresponding to the compartment pressure, and bysubjecting the vanes to hydraulic or spring pressure. for example, fromunderneath, forcing them into contact with the cam contour. Thehydraulic pressure so employed is taken from the high-pressure side ofthe machine and reduced by a pressure-reducing valve to a level justsufficient for the purpose.

lt is known that the rotor may be mounted in a housing of which oneportion is provided with ports and which is closed ofl on the other sideof the rotor by a disk having valve ports. It is also known that diskshaving ports may be mounted in the housing on both sides of the rotor.Particularly in the case of small machines having only one valve disk,where the housing, by virtue of its proportions of diameter and depth,is too rigid to yield. it will suflice to subject the valve disk to acompensating hydraulic pressure. However, this principle of designcannot be extended to large motors and pumps unless a riving atdimensions and weights of component parts that are excessive in aneconomic and engineering sense.

The invention proposes a rotary hydrostatic machine of the typedescribed. in which both valve plates are subjected to a pressurecompensating the pressure in the chambers. According to the invention,the valve disks are provided on the side far from the compartments witha cylindrical prolongation and, at the extremity thereof, with a flange,on the outside of which the compensating pressure is exerted. The valveplates, their cylindrical prolongation, and its terminal flange, form anannular space together with the housing. Further, it is proposed th atthe pressure subjected face of the flange and the under sides of thosevanes that are under working pressure on one surface only be placed incommunication through passages and supplied with pressure medium fromthe the anular space, its pressure being reduced in known manner by apressure-reducing valve to a fraction of the working pressure of themachine.

The size of the flanges is determined by the reduced working pressure,as applied to the underside of those vanes. which are subjected on theirone face to the working pressure and as applied to the face of theflanges and under consideration of the height of the pressure in thecompartments which must be compensated.

According to the invention, the valve disks are of equal shape and. withthe aid of a locating pin they are arranged like mirror pictures to theaxis of symmetry or to the centerline perpendicular thereto, each diskbeing equipped with a pressure-reducing valve and a check valve, whichaccording to the direction of rotation of the machine, are incommunication with the annular spaces and the pressure compensationspaces.

The conformation of the valve disks and their arrange ment on the twosides of the rotor according to the invention afford several advantagesover the prior art.

Since the pressure to which the under sides of the vanes must besubjected in their differential phase is a fixed quantity. and since theworking pressure is likewise a fixed quantity, it is possible to makethe terminal flange of the valve disks of such diameter that therequisite compensating pressure will result. A second advantage consistsin that the pressure to which the flange is subjected is simultaneouslyapplied to the under side of the vanes in their differential phase. Athird advantage of the invention is to be seen in the fact that on thefarside of each valve disk, an annular passage is formed, which isadequate for an undisturbed access and discharge of the pressure mediumand that at the same time short overall length of the machine, andsavings in weight are attained. The arrangement of the annular passagespermits compact accommodation of pressure-reducing and check valves. Theidentical pattern of the two valve plates also represents a considerableeconomy.

The device according to the invention will now be more fully describedwith reference to the accompanying drawings, but it should be understoodthat these are given by way of illustration and not of limitation andthat many changes in the details may be made without departing from thespirit of the invention.

in the drawings,

PEG. 1 is an axial section of the machine;

HQ. 2 is a cross section;

HO. 3 shows a valve disk as seen from the rotor.

Two housing portions 1, 2 are assembled with a cam ring 3 by means ofscrews 4 to form the housing of the machine. The cam ring together witha rotor 5, in known manner, forms a plurality of chambers 6, with asmany idle zones 7 where the rotor makes a sliding fit. Radial slots 8,are fitted with sliding vanes 10 to form compartments 6. The under sides11 of the vanes are acted upon by compression springs 12 set in axialchambers 13 through the body of the rotor 5. The cam ring and rotor aresandwiched between valve disks 14, 15 each prolonged axially on itsinside diameter by a tubular neck 16, 17 terminated by a flange 18, 19again paralleling the valve disk. The outside 2t), 21 of the valve disk,far from rotor 5, and the periphery of flange 18, 19 are in closecontact with the housing portion 1, 2. Inside the tubular neck 16, 17,the housing portion 1, 2 also makes contact. Between housing portions 1,2 and valve disks 14, 15 with their cylindrical prolongations 16, 17 andflanges 18, 19, annular chambers 22, 23 are thus formed aside thecompartments 6, for admission and discharge of pressure medium. Betweenhousing portions 1, 2 and the outside faces 24, 25 of the flanges andinside faces of the cylindrical prolongations 16, 17, narrow spaces 26,26', 27, 27 are provided to receive pressure medium.

Valve plates 14, 15 are identical, and held in position relative to camring 3 by a locating pin 28. They are provided with kidney-shaped ports29, 30 matching the chambers 6. Passages 31 establish communication fromthe annular spaces 22, 23 to the axial chambers 13 through the body ofthe rotor. Openings 32 communicate on one side with the axial chambers13 through the body of the rotor and on the other side, via passages 33,with the narrow spaces 26, 26', 27, 27' in housing portions 1 and 2.

Each valve plate contains a pressure-reducing valve 34 connected on itshigh-pressure side via a passage 35 with the annular space 22, 23 and onits low-pressure side with the narrow spaces 26, 26, 27, 27'. Oilleakage can return into annular space 22, 23 through a check valve 36.For this purpose the housing portions 1, 2 form annular channels 37together with the valve disks 14, 15 and with the rotors 5 which areconnected to each other by axial ducts 38 in the rotor 5. The checkvalves 36, which are closed under the pressure in the chambers 23 or 22,are contained in the return lines 39 from the annular channels 37 to thelow-pressure chambers 23 or 22.

In the following, suppose that the machine is functioning as a hydraulicmotor.

Medium flows from inlet 38 to outlet 39, turning the rotor in thedirection of the arrow. It enters through port 29 into compartments 6'and 6", and through passage 31 beneath the under side of vane 10',acting upon the surfaces of vanes 10" and 10" facing port 29, as well asupon both surfaces of vane 10'. Similarly it passes through the otherintake ports 29 into the corresponding compartments. The rotor is set inmotion and transmits the force of the medium to the shaft 40 of themachine. The medium is discharged, after doing its work, through theports 30--merely indicated as to position in FIG. 2- of the oppositevalve disk into annular chamber 23 to the outlet 39. Vane 10' is underworking pressure on both surfaces. It is not doing any work, but, inorder not to be pushed away from the contour of the cam ring, it must besubjected to working pressure from beneath over its entirecross-section, which is accomplished by supply of medium from annularchamber 22 through passage 31 in valve disk 14. Vanes 10" and 10" are inidle position; that is, only one of their surfaces is under workingpressure, there being no appreciable pressure on the other surface.These two vanes also must be pressed against the contour of the cam ringfrom beneath. However, the pressure required for this need amount toonly a portion of the working pressure, and is likewise taken fromannular space 22. The working pressure there prevailing is conducted viapassage 35 to pressure-reducing valve 34, which reduces it to a fractionof its value, for admission into the narrow space 26, 26' and, throughpassage 33, into the narrow space 27, 27. The same reduced pressure actson the outer faces 24, 25 of flanges 18, 19, keeping the valve disksfrom oflfsetting from the cam ring and rotor, since the flange areasubject to the reduced pressure is made sufficiently large to balancethe compartment pressure prevailing in the compartments 6.

The direction of rotation of the motor can be reversed by switchingpressure and return lines. Owing to the analogous design and arrangementof all parts, this requires no special conversion procedures. A changefrom motor to pump operation, as required for example in hoistingequipment, can also be made without prior adjustments.

What I claim is:

l. A hydrostatic machine comprising a first housing portion having aninlet opening for a pressure fluid, a second housing portion having anoutlet opening for said fluid, a cam ring interposed between saidhousing portions coaxially therewith, a pair of valve disks disposedbetween respective housing portions and said cam ring and extendingtransversely to the axis thereof, said disks laterally defining anannular space enclosed by said cam ring, a rotor coaxially journaled inone of said housing portions for rotation within said annular space,said rotor being provided with a plurality of generally radiallyslidable vanes engaging said cam ring, each of said valve disks beingprovided with a plurality of apertures connecting said space with one ofsaid openings in a respective housing portion. each of said disks beingformed with a respective sleeve extending axially outwardly from saidrotor into a respective housing portion, said sleeves being eachprovided with a terminal flange extending generally transversely to saidaxis, an inner surface of each of said flanges defining with itsrespective valve disk and housing portion an annular first chambercommunicating with a respective one of said openings, an outer surfaceof each flange defining with its respective housing portion an annularsecond chamber, sealing means interposed between said first and secondchambers, and means including pressure-reducing valves respectivelyinterconnecting the first and second chambers of each housing portion.

2. A hydrostatic machine comprising a first housing portion having aninlet opening for a pressure fluid, a second housing portion having anoutlet opening for said fluid. a cam ring interposed between saidhousing portions coaxially therewith, a pair or valve disks disposedsubstantially mirror-symmetrically between respective housing portionsand said cam ring and extending transversely to the axis thereof, saiddisks laterally defining an annular space enclosed by said cam ring andbeing angularly offset from each other by substantially a rotorcoaxially journaled in one of said housing portions for rotation withinsaid annular space, said rotor being providcd with a plurality ofgenerally radially slidable vanes engaging said cam ring, each of saidvalve disks being provided with a plurality of apertures connecting saidspace with one of said openings in a respective housing portion, each ofsaid disks being formed with 3 respective sleeve extending axiallyoutwardly from said rotor into a respective housing portion, saidsleeves being each provided with a terminal flange extending generallytrans versely to said axis, an inner surface of each of said flangesdefining with its respective valve disk and housing portion an annularfirst chamber communicating with a respective one of said openings, anouter surface of each flange defining with its respective housingportion an annular second chamber, sealing means interposed between saidfirst and second chambers, and means including pressurereducing valvesrespectively interconnecting the first and second chambers of eachhousing portion.

3. A machine according to claim 2 wherein said annular space issubdivided into a plurality of angularly equi-spaced Zones sequentiallyswept by each of said vanes, including working zones wherein said vanesare exposed to a fluid-pressure diflerential, transition zones whereinsaid differential is reduced to substantially zero and idle zoneswherein said vanes are substantially withdrawn into said rotor, saidrotor being provided with a plurality of fluid compartments each boundedby one of said vanes, at least one of said valve disks being formed witha plurality of first ports communicating with a respective first annularchamber and with the compartments of vanes sweeping said transitionzones, thereby urging the latter against said cam ring, the other ofsaid valve disks being provided with a plurality of second borescommunicating with a respective second annular chamber and with thecompartments of vanes sweeping said work ing and idle zones.

4. A machine according to claim 2 wherein each of said pressnre-reducingvalves is positioned and adapted to maintain a reduced pressure in arespective second annular chamber sufficient to counterbalance fluidpressure applied to the respective valvedisk surface facing said rotor.

5. A machine according to claim 2 wherein each of said valve disksdefines with said rotor a respective annular compartment, said rotorbeing provided with at least one axial duct interconnecting saidcompartments, and means including check valves interconnecting each ofsaid annular compartments with a respective one of said first annularchambers, said check valves being effective to block the flow of fluidunder pressure from said first annular chambers into said compartments.

References Cited in the file of this patent UNITED STATES PATENTS

